US2610317A - Power factor controlling and regulating device - Google Patents

Description

Sept. 9, 1952 FOWLER 2,610,317

POWER FACTOR CONTROLLING AND REGULATING DEVICE Filed April 8, 1948 2 SHEETS SHEET l homi y] t a g Q l k .5 1 r L: N Q N Iq Q A Q Q Q g 'Q Q 7 S m "3 n 3 R I \n n Girard Fowler INVENTOR.

Sept. 9, 1952 Filed A ril 8, 1948 G. FOWLER POWER FACTOR CONTROLLING AND REGULATING DEVICE 2 Sl-IEETSSHEET 2 -Fig.2.

EDBEEIEEIEIEIEQE Girard Fowler INVENTOR.

BY I wi ffiv p Patented Sept. 9, 1952 UNITED POWER FACTOR CONTROLLING AND REGULATING DEVICE Girard Fowler, Point Pleasant, W. Va.

Application April 8, 1948, Serial No. 19,808

3 Claims. (01. 323-105) This invention relates to power factor control devices for power generating or power consumin installations and it has for its main object to provide a simple and effective automatic controller adapted to produce a gradual correction of the power factor in accordance with changing existing conditions, which attempts to restore the optimal conditions or those conditions which have been selected.

It is known in the art that the reactance of the equipment connected with and energized from an A. C. network orpower house, imposes low powerfactorconditions on the network. Where the load is intermittent, pulsating or otherwise variable or where starting and stopping of electric appliances, cutting inv and out of electric valves, furnaces and similar loads occurs, transient low power conditions are produced which are superposed on the steady low power operating conditions and therefore power factor conditions can only be corrected by means of an automatic variable device. Such devices have been proposed for power houses, but it is of great advantage for the utility service as well as for the consumer to be able to correct the power factor in any installation supplied from the power lines.

It is therefore one of the primary objects of the invention to provide an automatic power factor controller or regulator which corrects the power factor of any installation or of any part thereof with which it is associated continuously according to the variations in the load entailing varying power factor conditions, and which is operated by the power factor meter which may be associated with any group of the consuming equipment.

It is a further object of the invention to provide an automatic power factor controller, correcting the power factor of any installation or of any part thereof by means of a power factor meter which is operating upon deflection of the meter indicating a change of the normal power factor condition, without using any device which is current consuming when not actually active in correcting the power factor.

It is a further object of the invention to provide an automatic power factor controller or regulator which is controlled electrically by means adapted to be operated exclusively on alternating currents, but which controls the addition, selection or reduction of power factor correcting compensating loads mechanically, by the mechanical control of switches controlling the connection of said compensating loads with the power line. I I g It is a further object'of the invention to'proo vide a series of power factor correcting com-, pensating loads to be added or eliminated successively and in steps and in further providing a mechanical means for bringing them into operation in a step by step fashion, said steps being controlled by the power factor meter. 1

It is a further object of the invention to provide a step by step control of the power factor correcting load by means of a motor the operation of which and the direction of operation of whichis controlled by the power factor meter, said motor running continuously as long as the power factor meter indicates that a phase shifting between voltage and current transgressing a certain limit occursv but which motor drives a rue-- chanical means acting in a series of separate suc-' cessive steps on a series of circuits adding or,- eliminating power factor correcting loads to the, load'existing in the power line. Y

It is a still further object of the invention to use discharge tubes and condensers for operatingselectively and by alternating currents only the relays which determine the operation and the direction of operation of the motor during the mechanical switch controlling means for thepower factor correcting load circuits.

It is a still further object of the invention to; provide limit switches which prevent a further operation of the motor when the mechanical means has reached the last switch of the series controlling the power correcting load circuit in the one and other direction.

Further and more specific objects will be apparent in the course of the detailed specification.

The invention is illustrated in the accompanying drawings showing one embodiment of the same. It is however to be understood that the embodiment shown has been selected in order to explain the principle of the invention and one of the preferred modes of applying it under certain conditions. The description and illustration of this specific example provide sufficient in formation to the expert skilled in this art to apply the said principle in cases differing from the example shown and no attempt is therefore made to provide a survey of the various embodiments of the invention. Modifications of the example shown are therefore not necessarily departures from the invention. 7

In the drawings:

Figure 1 is a diagram of the connections of the electric motor operating the controller.

Figure 2 is a diagrammatic elevational view of the bank of controlling switches and of the means for operating them. 3 H j Figure 3 is a cross sectional elevational view conditions may occur and in which therefore,

the power factor may either be lagging or leading. The former term is applied as well known to cases in which the voltage and the current have a phase difference with the former leading, this condition being produced by inductive loads, such as transformers, inductive motors and the like. The latter term is applied, as equally well known, to cases in which the current leads, this condition being produced by capacitors, such as used for power factor correction, by over' excited synchronous motors or the'like. For correction of the lagging power. factor, capacities are used, while leading power factors are corrected by inductances'. If. for instance a three phase network is used, it is customary to insert three condensers between the three phase lines for the purpose of power factor correction.

A low power factor condition corresponding to a large phase difference between current and voltage is objectionable in every type of power installation because it causes an overloading of the transformers, motors, generators etc. It is especially objectionable in the case of a power supplying utility service, as it causes a load which is not registered by the customary meters. The utility companies therefore add to those power consuming installations which may cause a re duction of the power factor a special meter in- (heating the phase difference between current and voltage or registering the power factor and a separate charge is made in accordance with the meter indications to the consumer using an equipment under low power factor conditions. The meter usually registers only a power factor decrease which passes acertain fixed limit which may be tolerated.

The presentinvention makes use of this meter the construction of which does not differ from that of the customary meters so that it need not be described in detail.

The customary meter is shown at I and it is provided with a pointer II, occupying a central position, such as shown, when the voltage and the current are in phase, but moving to the right or to the'left when the power factor is leading or lagging respectively. Either the shaft of the pointer or preferably an arm resiliently connected with the pointer, as diagrammatically indicated, moves an insulated contact arm I2, adapted to turn .around a fulcrum or pivot i3 and cooperating with two insulated fixed contacts I4 and I5, which are adjustable individually.

The contact arm I2 carries a contact piece adapted to cooperate with contacts I 4 and I5 which is connected by a conducting strip or wire (not specially indicated) with a conductor 2|, leading to the pivot or fulcrum I3. Conductor 2| contains a resistance 40 and is connected with conductor 26 of a line branching on from the branch line 30', 32 leading for instance from two phase conductors 3| ,33 of the three phase power supply line 3 33; 35..

The two fixed adjustable contacts I4, I5 (2011-! trol circuits I'I I8 which include the starting or designated by referencenumerals H0,

4 grid electrodes I9, 20 of two discharge tubes 22, 24. These tubes may, for instance, be cold cathode gas triode tubes of the ionic cathode glow discharge type; but it will be manifest that other types of tubes may also be used. The cathodes 23, 25 of the said tubes are connected with the second conductor 21 of the line branching on from branch line 30, 32, by means of leads :32, 44, which contain limit switches .50, 52 respectively to be described below. The line 25, 2'! may also contain the double pole single throw switch 29 which permits the disconnection of the meter and discharge tubes.

The plate circuits it, 48 of the two discharge tubes contain adjustable resistances 41, 49 and relays G0, 62 provided with relay armature contacts 64, 60. Each relay contact cooperates with two fixed contacts 63, B5 and 61, 69 respectively. A condenser I0, 12 is connected across the relay winding, bridging the same.

The relay contacts 54, 66 control a motor which is preferably provided with a series winding 8I connected with one of. the conductors 32. of branch line 30, 32. The branch. line portion leading to the motor 80 may be provided with a separate double pole single throw switch 83. While the armature 84 of the motor is connected with the relay contacts 64, 66 by means of conductors 8B, 88 respectively, the two interconnected fixed rest contacts 63, 6? are connected with the field winding BI by conductor 8'! while. the two interconnected fixed operative contacts 65, 69 are connected with conductor 30' of the branch line.

The motor 80 as seen may run in both direc-' tions, according to the position of the relay armatures 64 and 66 which reverse the flow of. currentthrough the armature of the motor 30.

The corrective load devices consist of capacitors I00, I85, I02 (Figure 6), connected between the lines I03, I04, I05, connected with the power lines. In most cases the loads formed by transformers, motors and resistances are prevalently inductive and their influence on the power factor is compensated by corrective capacitors. The appearance of a leading power factor in such cases is mainly the consequence of an over compensation due to a decrease of the inductive load without corresponding reduction of the compensating capacitive load. Under these conditions merely capacitors need be used for maintaining the power factor at an optimal value, the numbers or capacities of which are increased or decreased. It will however be understood that while the present example is based on the above explained conditions, the invention may be carried into effect in practically the same manner or only with obvious modifications if some of the compensating-loads are inductances.

Each compensating capacity which consists in the case of a three phase power line of the group of three capacitors I00, I0 I, I02 is connected with the power line or a branch thereof by means of a polarized A. C. relay or magnetic switch 90, with an armature carrying three relay contacts 9|, 92, 93, one for each line. The circuit 04 of the relay is connected with two of the phase conductors and is controlled by a mercury switch H0.

All the mercury switches IIO controlling the pieces H6. They form a switch bank generally indicated at H2. The individual switches are H02) Each of them is mounted on a switch holder IIB having the form of a bell crank lever which is pivoted on the frame III near its knee by means of lugs I22. The longer arm III! of the switch holder carries the mercury switch I I0, I We, I I0b near its end while the shorter arm I lea is provided with a lug or projection I24 turned toward the frame. Normally the bell crank lever rests'on the frame. In this position (indicated in dotted lines) the mercury switch is outwardly inclined the mercury drop being on the outer end of the switch tube while the contacts II! are at the inner end, near to the frame. The relay circuit is therefore open in the position of rest. The contacts Ill are connected with a contact bank I 2 I mounted on the upper portion of the frame by suitable flexible connections.

Below the zone in which the switch holders are pivoted the frame is provided with a slot I in which a cam member I20-may move. This cam member consists of a grooved rail preferably provided with an extending ledge adapted to slide along the frame within the slot and guiding itself by the groove engaging the frame portion above the slot and by the ledge applied against its surface. The cam member is of considerable length, and may pass through the end pieces H6 of the frame by means of suitable openings II4. The length of the cam member must be at least equal to the length of the switch bank.

Said cam member I20 is provided with a guide lug I28 or a plurality of guide lugs, each provided with a threaded opening I29 through which a threaded spindle I30 passes. This spindle is journalled in the end pieces and secured against longitudinal movement by suitable collars. It is driven by the motor 80 by means of suitable reduction gears enclosed in the gear box I32.

The rotation of the spindle in the one or other direction advances the cam member I20 longitudinally in the one or other direction. While so advanced the cam member I20 which is provided with a tapering front end, lifts the lugs I24 in whose vicinity it is advanced and thereby turns the downwardly pointing arm II9 of the switch holder II8 upwardly. The mercury switch III! is moved to an inwardly inclined position (as shown in full lines) in which the mercury drop rests on the end of the switch turned towards the frame and closes the contacts I I1 arranged on this end.

The outermost switches of the switch bank are formed by the limit switches and 52 controlling the admission of current to the tubes 22, 24. These switches have the same construction as the switches I I0 but switch 50 differs from the other switches insofar as the contacts II'Ia are on the other or outer end as shown in Figure 5. Therefore switch 50 breaks the circuits when lifted by the cam member and cuts out the tube 22. Similarly switch 52 cuts out tube 24.

" From the above detailed description of the apparatus the operation will be clearly understood.

Let it be assumed that switches 29 and 83 are closed and that at first a balanced condition exists with the voltage and current in phase and that by some change, for instance by the switching in of an inductive load, a lagging power factor is produced While the pointer of the power factor meter at first was in its middle position, the movement of the pointer II to the left moves contact arm I2 to the right and therefore its contact piece comes into contact with the fixed contact I5 thereby energizing the starting electrode I9 of tube 22. The circuit starts at 33 and runs over 32, closed switch 29, 26, 40, 2|, I2, I5, I! to electrode I9.

During the positive half wave in conductor 33, which coincides with a negative phase in conductor 3| the starting grid I9 gets a positive charge while a negative charge is imparted to the cathode 23 from 3| over 30, closed switch 29, 21, 42 and closed limit switch 50. The plate of the tube is also at a positive potential over 46, 41, and therefore the tube fires and the plate current energizes the relay 60 and charges the condenser I0. During the negative Ilalf wave the tube is de-energized but the condenser 10 discharges itself over the relay 60 which is in parallel with it. The next positive half wave repeats the performance of the first positive half wave and so forth so that during both the positive and the negative wave unidirectional current is flowin through the relay 60 as long as current flows through the tube. Relay 60 therefore attracts its armature 64 and holds it in the position indicated in dotted lines in which it rests on contact 65 as long as the grid electrode I9 is connected with the net conductor 32. 1

In this position the current flows from 33 and 32 over closed switch 83 and field windings 8I of motor over 81 and 01, 66, 86 to armature 84 and over 88, 64, 65 and 30 t0 3I. During the positive phase in 33, for instance, the current, as will be observed, will flow through the armature and field winding in the direction of the arrow with one point. The motor will therefore rotate in a definite direction.

Upon rotation of the motor 80 the spindle I30 is rotated in such a direction by means of gears that the threaded guide lug I28 engaging the spindle moves from the left to the right in Figure 2. The cam member I20 is advanced and trips a mercury switch IIO which closes the circuit of polarized relay 90. Contacts 9|, 92, 33 are therefore closed and a capacitive load IOI, I02, I03 is now put on the line, which compensates the influence of the inductive load on the power factor.

If this compensation is sufficient the switching in of the condensers will cause the meter to swing back and further movement of motor 80 is stopped. If the compensation was not sufficient, the pointer II will still be on the left side and operation will continue, a second mercury switch is tripped, a further capacitive load is put on the line and the operation continues automatically until compensation is achieved.

Let it now be assumed that all the capacitive loads have been switched in, but that compensation has not been effected. In this case the cam member I25 has been advanced to the extreme right and after having tripped all the switches II-S now trips the last switch 50. This switch as will be remembered is the limit switch which was closed when not tripped and it is now opened when the cam member I20 lifts it and cuts out any further operation by interrupting the tube circuits. As all compensating means have been switched in, there is no need for further operation in this direction and the operation stops. The attendant may be informed of this condition in any appropriate manner, but this is not shown in the drawings.

Should the inductive load decrease in this or another position of the apparatus in which capacitive loads have been connected with the line, the pointer of the power factor meter will move to the right side in Figure l as now'the current leads. Thereby arm I2 moves to the left and contacts the fixed contact I4. This connects line 33 with starting grid electrode 20 of tube 24 aeioeie ove the connections above mentioned to cont to ohtaet and time 1. Now relay 6? openate n a manner analogous to that de cribed. ion w h rela 60,- Arma ure a opts the tioh n d tt d line an current flows new fr m 2 o er 8!, contact 63. 164, 8..

arma ur 284, B 9 to 30- t wi l be obser ed that wh e the current hrou h the field winding, say n The the p siti e pha is t l ihdi et d. hyhe some ar ows pla ed h ar the el W lli hss, th direction f h cur ent flo thro g the rm ihe is how ndic e y the ar o ith tw Th re a i e ho of c rren is er fore d. an the motor 81 ro ates in the opposite refine the spindl t!) rota es in of the s ind e ow m ves the I20. i I11 gh to le n Fi ure 2. The erh m ,..be the efor Wit draw from s itch ewiteh 8 thereby u tin ut he eeheo tive loads.- The moto sto s so n a he com: pensation is obtained and current and voltage are n hase or a e onl out of ph for t chase ahsl whi h i lerated Sho ld the. capacitive l ad sti e ceed the in u ive lo d when the c m member ha rea he h l t end of the s itch H1 tch .2 l fina ly he ohehedahdiurthe o era o il e ut o a ree y tated it may be ad isable s he which a iti e loads are the l ne to provide compensating inductive loads instead o the capa itiv l ad the circuits on. he le end o the series.- I will he s en hat the s stem as escribed ro ides a ver precise. control o the o e ac tor as ste s. as may he consi ered s su table which doe no onsume a our-rent h eht when ac a! co e ti e o eration- M eove the s stem is fully ah ma cahd o: tee he utilit ervice a ainst he und irable ove loads of the enerators as wel a the 9911*- sumer against undesirable overloading of his equi men a d unde a le char es or W o erload It l. he un e teodthat c n truct e ch n es o an. hhe en ial atur ill n t ef c he m n title and ope ation as a o e esc ed.-

Haih d c ibed, h in ention, hat is elai he as new is;

1 .A ower fac or c n r ller r o -whos alternating en o er lines with ser es o power factor correcting devices, connected and disconnected with said power lines by a series of switches operated in succession by a reversible electric motor, said controller further including a power factor meter provided with. contacts alternatively closed upon deviation of the power factor from a predetermined value in different directions comprising alternating currents carry.-. ing circuits connected with the contacts of the said power factor meter, a grid controlled electronic tube in each of said power factor cone trolled alternating current circuits, said tube being provided with cathode, plate and grid, the latterbeing directly connected with one of the power factor meter controlled alternating current circuits, an ener iz ng circuit for each of said tubes, directly connected with the alternating current power lines, the power factor of which issupervised by the Power factor meter, a relay, a condenser, the latter connected in harallelto the relay a ranged in he pla e rcui of each tube, .arelay armatu e for ea of said relays, arranged t ado t wo contact positions. wo s at nary con acts for each relay a mature, on fo the p tion o r an the other t r he rgize p s t on of the r l y fie ind n s and hel ci c its an an arm tu e circuit ,for sa ersib e e ectr c mo he re ay a m ee oi he relay being o nneet w h the a d armo tore eirohi oi the re er b motor, and e rest ontac s o o h re y armeture conn c ed ara lel and with one side of the field w nding, th othe i e of s id indin bein c n ec d ith one of the power ine while the s ationary contacts o the relay a mature f r e ene ed. po it on of t e same a e c nnected in parallel, o h. being connected with one of the po er lines. the relays thus receiving direct current pulses. operating them and when operated changing the relative direction of current flow in the field and armature winding of the reversing electric motor.

-2. In a power factor controlling apparatus as claimed in claim 1, a number of compensatory units directing the power factor, each consisting of elements symmetrically inserted between the polyphase lines, a separate relay for each of said units simultaneously switching in and out the connections of each unit with the polyphase lines, an energizing circuit for said relay "branching off from said power lines, a switch bank with tilt: able mercury switches, each mercury switch con, trolling the energizing circuit of one of said relays, said switch bank further having a frame plate provided with a longitudinal slot, bellcrank levers pivotally mounted-on said frameplate along said slot, one end of each bellcrank lever supporting said tiltable mercury switch, the other ends of the bellcrank levers being aligned and resting on the frame plate to hold the mercury switches in their open position, a slide member slidably arranged in said slot of said frame and sliding along the line along which said aligned bellcrank lever ends rest to lift the said ends sue..- cessively during its movement, thus bringing the mercury switches successively one by one into their circuit closing position, a threaded guiding lug on said slide, a rotatable spindle engaging said threaded lug, said spindle being driven by the reversible electric motor.

3. A power factor controller as claimed in claim 1, wherein the first and last mercury switch of the switch bank are limit switches, operated when all power factor compensating units have been switched in or out respectively, said first and last switches of the switch bank being arranged in the energizing circuit of the electronic tubes respectively.

GIRARD FOWLER:

le of h s atent:

STATES PA'IENTS Number Name Date 1,669,112 Winter n May 28, 1928 1,951,733 Kniesznei Mar. 20, 1934 1,959,298 Levy May 15, 1934 2,078,667 Kado Apr. 27, 1937 2,232,993 Berquist T, Feb. 25, 1941 2,243,584 Toda May 27, 1941 2,460,467 I Nelson Feb. 1, 1949

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